Added in API level 1

X509Certificate

abstract class X509Certificate : Certificate, X509Extension

kotlin.Any
↳	java.security.cert.Certificate
	↳	java.security.cert.X509Certificate

Abstract class for X.509 certificates. This provides a standard way to access all the attributes of an X.509 certificate.

In June of 1996, the basic X.509 v3 format was completed by ISO/IEC and ANSI X9, which is described below in ASN.1:

Certificate  ::=  SEQUENCE  {
      tbsCertificate       TBSCertificate,
      signatureAlgorithm   AlgorithmIdentifier,
      signature            BIT STRING  }

These certificates are widely used to support authentication and other functionality in Internet security systems. Common applications include Privacy Enhanced Mail (PEM), Transport Layer Security (SSL), code signing for trusted software distribution, and Secure Electronic Transactions (SET).

These certificates are managed and vouched for by Certificate Authorities (CAs). CAs are services which create certificates by placing data in the X.509 standard format and then digitally signing that data. CAs act as trusted third parties, making introductions between principals who have no direct knowledge of each other. CA certificates are either signed by themselves, or by some other CA such as a "root" CA.

More information can be found in RFC 3280: Internet X.509 Public Key Infrastructure Certificate and CRL Profile.

The ASN.1 definition of tbsCertificate is:

TBSCertificate  ::=  SEQUENCE  {
      version         [0]  EXPLICIT Version DEFAULT v1,
      serialNumber         CertificateSerialNumber,
      signature            AlgorithmIdentifier,
      issuer               Name,
      validity             Validity,
      subject              Name,
      subjectPublicKeyInfo SubjectPublicKeyInfo,
      issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL,
                           -- If present, version must be v2 or v3
      subjectUniqueID [2]  IMPLICIT UniqueIdentifier OPTIONAL,
                           -- If present, version must be v2 or v3
      extensions      [3]  EXPLICIT Extensions OPTIONAL
                           -- If present, version must be v3
      }

Certificates are instantiated using a certificate factory. The following is an example of how to instantiate an X.509 certificate:

try (InputStream inStream = new FileInputStream("fileName-of-cert")) {
      CertificateFactory cf = CertificateFactory.getInstance("X.509");
      X509Certificate cert = (X509Certificate)cf.generateCertificate(inStream);
  }

Summary

Protected constructors
`X509Certificate()` Constructor for X.

Public methods
abstract Unit	`checkValidity()` Checks that the certificate is currently valid.
abstract Unit	`checkValidity(date: Date!)` Checks that the given date is within the certificate's validity period.
abstract Int	`getBasicConstraints()` Gets the certificate constraints path length from the critical `BasicConstraints` extension, (OID = 2.5.29.19).
open MutableList<String!>!	`getExtendedKeyUsage()` Gets an unmodifiable list of Strings representing the OBJECT IDENTIFIERs of the `ExtKeyUsageSyntax` field of the extended key usage extension, (OID = 2.5.29.37).
open MutableCollection<MutableList<*>!>!	`getIssuerAlternativeNames()` Gets an immutable collection of issuer alternative names from the `IssuerAltName` extension, (OID = 2.5.29.18).
abstract Principal!	`getIssuerDN()` Denigrated, replaced by getIssuerX500Principal().
abstract BooleanArray!	`getIssuerUniqueID()` Gets the `issuerUniqueID` value from the certificate.
open X500Principal!	`getIssuerX500Principal()` Returns the issuer (issuer distinguished name) value from the certificate as an `X500Principal`.
abstract BooleanArray!	`getKeyUsage()` Gets a boolean array representing bits of the `KeyUsage` extension, (OID = 2.5.29.15).
abstract Date!	`getNotAfter()` Gets the `notAfter` date from the validity period of the certificate.
abstract Date!	`getNotBefore()` Gets the `notBefore` date from the validity period of the certificate.
abstract BigInteger!	`getSerialNumber()` Gets the `serialNumber` value from the certificate.
abstract String!	`getSigAlgName()` Gets the signature algorithm name for the certificate signature algorithm.
abstract String!	`getSigAlgOID()` Gets the signature algorithm OID string from the certificate.
abstract ByteArray!	`getSigAlgParams()` Gets the DER-encoded signature algorithm parameters from this certificate's signature algorithm.
abstract ByteArray!	`getSignature()` Gets the `signature` value (the raw signature bits) from the certificate.
open MutableCollection<MutableList<*>!>!	`getSubjectAlternativeNames()` Gets an immutable collection of subject alternative names from the `SubjectAltName` extension, (OID = 2.5.29.17).
abstract Principal!	`getSubjectDN()` Denigrated, replaced by getSubjectX500Principal().
abstract BooleanArray!	`getSubjectUniqueID()` Gets the `subjectUniqueID` value from the certificate.
open X500Principal!	`getSubjectX500Principal()` Returns the subject (subject distinguished name) value from the certificate as an `X500Principal`.
abstract ByteArray!	`getTBSCertificate()` Gets the DER-encoded certificate information, the `tbsCertificate` from this certificate.
abstract Int	`getVersion()` Gets the `version` (version number) value from the certificate.
open Unit	`verify(key: PublicKey!, sigProvider: Provider!)` Verifies that this certificate was signed using the private key that corresponds to the specified public key.

Inherited functions

From class Certificate

`Boolean`	`equals(other: Any?)` Compares this certificate for equality with the specified object. If the `other` object is an `instanceof` `Certificate`, then its encoded form is retrieved and compared with the encoded form of this certificate.
`ByteArray!`	`getEncoded()` Returns the encoded form of this certificate. It is assumed that each certificate type would have only a single form of encoding; for example, X.509 certificates would be encoded as ASN.1 DER.
`PublicKey!`	`getPublicKey()` Gets the public key from this certificate.
`String!`	`getType()` Returns the type of this certificate.
`Int`	`hashCode()` Returns a hashcode value for this certificate from its encoded form.
`String`	`toString()` Returns a string representation of this certificate.
`Unit`	`verify(key: PublicKey!)` Verifies that this certificate was signed using the private key that corresponds to the specified public key.
`Unit`	`verify(key: PublicKey!, sigProvider: String!)` Verifies that this certificate was signed using the private key that corresponds to the specified public key. This method uses the signature verification engine supplied by the specified provider.
`Any!`	`writeReplace()` Replace the Certificate to be serialized.

From class X509Extension

MutableSet<String!>!

getCriticalExtensionOIDs()

Gets a Set of the OID strings for the extension(s) marked CRITICAL in the certificate/CRL managed by the object implementing this interface. Here is sample code to get a Set of critical extensions from an X509Certificate and print the OIDs:

<code>X509Certificate cert = null;
  try (InputStream inStrm = new FileInputStream("DER-encoded-Cert")) {
      CertificateFactory cf = CertificateFactory.getInstance("X.509");
      cert = (X509Certificate)cf.generateCertificate(inStrm);
  }
 
  Set&lt;String&gt; critSet = cert.getCriticalExtensionOIDs();
  if (critSet != null &amp;&amp; !critSet.isEmpty()) {
      System.out.println("Set of critical extensions:");
      for (String oid : critSet) {
          System.out.println(oid);
      }
  }
  </code>

ByteArray!

getExtensionValue(oid: String!)

Gets the DER-encoded OCTET string for the extension value (extnValue) identified by the passed-in oid String. The oid string is represented by a set of nonnegative whole numbers separated by periods.

For example:

Examples of OIDs and extension names

OID (Object Identifier)	Extension Name
2.5.29.14	SubjectKeyIdentifier
2.5.29.15	KeyUsage
2.5.29.16	PrivateKeyUsage
2.5.29.17	SubjectAlternativeName
2.5.29.18	IssuerAlternativeName
2.5.29.19	BasicConstraints
2.5.29.30	NameConstraints
2.5.29.33	PolicyMappings
2.5.29.35	AuthorityKeyIdentifier
2.5.29.36	PolicyConstraints

MutableSet<String!>!

getNonCriticalExtensionOIDs()

Gets a Set of the OID strings for the extension(s) marked NON-CRITICAL in the certificate/CRL managed by the object implementing this interface. Here is sample code to get a Set of non-critical extensions from an X509CRL revoked certificate entry and print the OIDs:

<code>CertificateFactory cf = null;
  X509CRL crl = null;
  try (InputStream inStrm = new FileInputStream("DER-encoded-CRL")) {
      cf = CertificateFactory.getInstance("X.509");
      crl = (X509CRL)cf.generateCRL(inStrm);
  }
 
  byte[] certData = &lt;DER-encoded certificate data&gt;
  ByteArrayInputStream bais = new ByteArrayInputStream(certData);
  X509Certificate cert = (X509Certificate)cf.generateCertificate(bais);
  X509CRLEntry badCert =
               crl.getRevokedCertificate(cert.getSerialNumber());
 
  if (badCert != null) {
      Set&lt;String&gt; nonCritSet = badCert.getNonCriticalExtensionOIDs();
      if (nonCritSet != null)
          for (String oid : nonCritSet) {
              System.out.println(oid);
          }
  }
  </code>

Boolean

hasUnsupportedCriticalExtension()

Check if there is a critical extension that is not supported.

Protected constructors

X509Certificate

Added in API level 1

protected X509Certificate()

Constructor for X.509 certificates.

Public methods

checkValidity

Added in API level 1

abstract fun checkValidity(): Unit

Checks that the certificate is currently valid. It is if the current date and time are within the validity period given in the certificate.

The validity period consists of two date/time values: the first and last dates (and times) on which the certificate is valid. It is defined in ASN.1 as:

validity             Validity
 
  Validity ::= SEQUENCE {
      notBefore      CertificateValidityDate,
      notAfter       CertificateValidityDate }
 
  CertificateValidityDate ::= CHOICE {
      utcTime        UTCTime,
      generalTime    GeneralizedTime }

Exceptions
`java.security.cert.CertificateExpiredException`	if the certificate has expired.
`java.security.cert.CertificateNotYetValidException`	if the certificate is not yet valid.

checkValidity

Added in API level 1

abstract fun checkValidity(date: Date!): Unit

Checks that the given date is within the certificate's validity period. In other words, this determines whether the certificate would be valid at the given date/time.

Parameters
`date`	Date!: the Date to check against to see if this certificate is valid at that date/time.

Exceptions
`java.security.cert.CertificateExpiredException`	if the certificate has expired with respect to the `date` supplied.
`java.security.cert.CertificateNotYetValidException`	if the certificate is not yet valid with respect to the `date` supplied.

See Also

#checkValidity()

getBasicConstraints

Added in API level 1

abstract fun getBasicConstraints(): Int

Gets the certificate constraints path length from the critical BasicConstraints extension, (OID = 2.5.29.19).

The basic constraints extension identifies whether the subject of the certificate is a Certificate Authority (CA) and how deep a certification path may exist through that CA. The pathLenConstraint field (see below) is meaningful only if cA is set to TRUE. In this case, it gives the maximum number of CA certificates that may follow this certificate in a certification path. A value of zero indicates that only an end-entity certificate may follow in the path.

The ASN.1 definition for this is:

BasicConstraints ::= SEQUENCE {
      cA                  BOOLEAN DEFAULT FALSE,
      pathLenConstraint   INTEGER (0..MAX) OPTIONAL }

Return
`Int`	the value of `pathLenConstraint` if the BasicConstraints extension is present in the certificate and the subject of the certificate is a CA, otherwise -1. If the subject of the certificate is a CA and `pathLenConstraint` does not appear, `Integer.MAX_VALUE` is returned to indicate that there is no limit to the allowed length of the certification path.

getExtendedKeyUsage

Added in API level 1

open fun getExtendedKeyUsage(): MutableList<String!>!

Gets an unmodifiable list of Strings representing the OBJECT IDENTIFIERs of the ExtKeyUsageSyntax field of the extended key usage extension, (OID = 2.5.29.37). It indicates one or more purposes for which the certified public key may be used, in addition to or in place of the basic purposes indicated in the key usage extension field. The ASN.1 definition for this is:

ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
 
  KeyPurposeId ::= OBJECT IDENTIFIER

Key purposes may be defined by any organization with a need. Object identifiers used to identify key purposes shall be assigned in accordance with IANA or ITU-T Rec. X.660 | ISO/IEC/ITU 9834-1.

This method was added to version 1.4 of the Java 2 Platform Standard Edition. In order to maintain backwards compatibility with existing service providers, this method is not abstract and it provides a default implementation. Subclasses should override this method with a correct implementation.

Return
`MutableList<String!>!`	the ExtendedKeyUsage extension of this certificate, as an unmodifiable list of object identifiers represented as Strings. Returns null if this certificate does not contain an ExtendedKeyUsage extension.

Exceptions
`java.security.cert.CertificateParsingException`	if the extension cannot be decoded

getIssuerAlternativeNames

Added in API level 1

open fun getIssuerAlternativeNames(): MutableCollection<MutableList<*>!>!

Gets an immutable collection of issuer alternative names from the IssuerAltName extension, (OID = 2.5.29.18).

The ASN.1 definition of the IssuerAltName extension is:

IssuerAltName ::= GeneralNames

The ASN.1 definition of GeneralNames is defined in getSubjectAlternativeNames.

If this certificate does not contain an IssuerAltName extension, null is returned. Otherwise, a Collection is returned with an entry representing each GeneralName included in the extension. Each entry is a List whose first entry is an Integer (the name type, 0-8) and whose second entry is a String or a byte array (the name, in string or ASN.1 DER encoded form, respectively). For more details about the formats used for each name type, see the getSubjectAlternativeNames method.

Note that the Collection returned may contain more than one name of the same type. Also, note that the returned Collection is immutable and any entries containing byte arrays are cloned to protect against subsequent modifications.

Return
`MutableCollection<MutableList<*>!>!`	an immutable `Collection` of issuer alternative names (or `null`)

Exceptions
`java.security.cert.CertificateParsingException`	if the extension cannot be decoded

getIssuerDN

Added in API level 1

abstract fun getIssuerDN(): Principal!

Denigrated, replaced by getIssuerX500Principal(). This method returns the issuer as an implementation specific Principal object, which should not be relied upon by portable code.

Gets the issuer (issuer distinguished name) value from the certificate. The issuer name identifies the entity that signed (and issued) the certificate.

The issuer name field contains an X.500 distinguished name (DN). The ASN.1 definition for this is:

issuer    Name
 
  Name ::= CHOICE { RDNSequence }
  RDNSequence ::= SEQUENCE OF RelativeDistinguishedName
  RelativeDistinguishedName ::=
      SET OF AttributeValueAssertion
 
  AttributeValueAssertion ::= SEQUENCE {
                                AttributeType,
                                AttributeValue }
  AttributeType ::= OBJECT IDENTIFIER
  AttributeValue ::= ANY

The Name describes a hierarchical name composed of attributes, such as country name, and corresponding values, such as US. The type of the AttributeValue component is determined by the AttributeType; in general it will be a directoryString. A directoryString is usually one of PrintableString, TeletexString or UniversalString.

Return
`Principal!`	a Principal whose name is the issuer distinguished name.

getIssuerUniqueID

Added in API level 1

abstract fun getIssuerUniqueID(): BooleanArray!

Gets the issuerUniqueID value from the certificate. The issuer unique identifier is present in the certificate to handle the possibility of reuse of issuer names over time. RFC 3280 recommends that names not be reused and that conforming certificates not make use of unique identifiers. Applications conforming to that profile should be capable of parsing unique identifiers and making comparisons.

The ASN.1 definition for this is:

issuerUniqueID  [1]  IMPLICIT UniqueIdentifier OPTIONAL
 
  UniqueIdentifier  ::=  BIT STRING

Return
`BooleanArray!`	the issuer unique identifier or null if it is not present in the certificate.

getIssuerX500Principal

Added in API level 1

open fun getIssuerX500Principal(): X500Principal!

Returns the issuer (issuer distinguished name) value from the certificate as an X500Principal.

It is recommended that subclasses override this method.

Return
`X500Principal!`	an `X500Principal` representing the issuer distinguished name

getKeyUsage

Added in API level 1

abstract fun getKeyUsage(): BooleanArray!

Gets a boolean array representing bits of the KeyUsage extension, (OID = 2.5.29.15). The key usage extension defines the purpose (e.g., encipherment, signature, certificate signing) of the key contained in the certificate. The ASN.1 definition for this is:

KeyUsage ::= BIT STRING {
      digitalSignature        (0),
      nonRepudiation          (1),
      keyEncipherment         (2),
      dataEncipherment        (3),
      keyAgreement            (4),
      keyCertSign             (5),
      cRLSign                 (6),
      encipherOnly            (7),
      decipherOnly            (8) }

RFC 3280 recommends that when used, this be marked as a critical extension.

Return

BooleanArray! the KeyUsage extension of this certificate, represented as an array of booleans. The order of KeyUsage values in the array is the same as in the above ASN.1 definition. The array will contain a value for each KeyUsage defined above. If the KeyUsage list encoded in the certificate is longer than the above list, it will not be truncated. Returns null if this certificate does not contain a KeyUsage extension.

Return
`BooleanArray!`	the KeyUsage extension of this certificate, represented as an array of booleans. The order of KeyUsage values in the array is the same as in the above ASN.1 definition. The array will contain a value for each KeyUsage defined above. If the KeyUsage list encoded in the certificate is longer than the above list, it will not be truncated. Returns null if this certificate does not contain a KeyUsage extension.

getNotAfter

Added in API level 1

abstract fun getNotAfter(): Date!

Gets the notAfter date from the validity period of the certificate. See getNotBefore for relevant ASN.1 definitions.

Return
`Date!`	the end date of the validity period.

See Also

getNotBefore

Added in API level 1

abstract fun getNotBefore(): Date!

Gets the notBefore date from the validity period of the certificate. The relevant ASN.1 definitions are:

validity             Validity
 
  Validity ::= SEQUENCE {
      notBefore      CertificateValidityDate,
      notAfter       CertificateValidityDate }
 
  CertificateValidityDate ::= CHOICE {
      utcTime        UTCTime,
      generalTime    GeneralizedTime }

Return
`Date!`	the start date of the validity period.

See Also

getSerialNumber

Added in API level 1

abstract fun getSerialNumber(): BigInteger!

Gets the serialNumber value from the certificate. The serial number is an integer assigned by the certification authority to each certificate. It must be unique for each certificate issued by a given CA (i.e., the issuer name and serial number identify a unique certificate). The ASN.1 definition for this is:

serialNumber     CertificateSerialNumber
 
  CertificateSerialNumber  ::=  INTEGER

Return
`BigInteger!`	the serial number.

getSigAlgName

Added in API level 1

abstract fun getSigAlgName(): String!

Gets the signature algorithm name for the certificate signature algorithm. An example is the string "SHA256withRSA". The ASN.1 definition for this is:

signatureAlgorithm   AlgorithmIdentifier
 
  AlgorithmIdentifier  ::=  SEQUENCE  {
      algorithm               OBJECT IDENTIFIER,
      parameters              ANY DEFINED BY algorithm OPTIONAL  }
                              -- contains a value of the type
                              -- registered for use with the
                              -- algorithm object identifier value

The algorithm name is determined from the algorithm OID string.

Return
`String!`	the signature algorithm name.

getSigAlgOID

Added in API level 1

abstract fun getSigAlgOID(): String!

Gets the signature algorithm OID string from the certificate. An OID is represented by a set of nonnegative whole numbers separated by periods. For example, the string "1.2.840.10040.4.3" identifies the SHA-1 with DSA signature algorithm defined in RFC 3279: Algorithms and Identifiers for the Internet X.509 Public Key Infrastructure Certificate and CRL Profile.

See getSigAlgName for relevant ASN.1 definitions.

Return
`String!`	the signature algorithm OID string.

getSigAlgParams

Added in API level 1

abstract fun getSigAlgParams(): ByteArray!

Gets the DER-encoded signature algorithm parameters from this certificate's signature algorithm. In most cases, the signature algorithm parameters are null; the parameters are usually supplied with the certificate's public key. If access to individual parameter values is needed then use AlgorithmParameters and instantiate with the name returned by getSigAlgName.

See getSigAlgName for relevant ASN.1 definitions.

Return
`ByteArray!`	the DER-encoded signature algorithm parameters, or null if no parameters are present.

getSignature

Added in API level 1

abstract fun getSignature(): ByteArray!

Gets the signature value (the raw signature bits) from the certificate. The ASN.1 definition for this is:

signature     BIT STRING

Return
`ByteArray!`	the signature.

getSubjectAlternativeNames

Added in API level 1

open fun getSubjectAlternativeNames(): MutableCollection<MutableList<*>!>!

Gets an immutable collection of subject alternative names from the SubjectAltName extension, (OID = 2.5.29.17).

The ASN.1 definition of the SubjectAltName extension is:

SubjectAltName ::= GeneralNames
 
  GeneralNames :: = SEQUENCE SIZE (1..MAX) OF GeneralName
 
  GeneralName ::= CHOICE {
       otherName                       [0]     OtherName,
       rfc822Name                      [1]     IA5String,
       dNSName                         [2]     IA5String,
       x400Address                     [3]     ORAddress,
       directoryName                   [4]     Name,
       ediPartyName                    [5]     EDIPartyName,
       uniformResourceIdentifier       [6]     IA5String,
       iPAddress                       [7]     OCTET STRING,
       registeredID                    [8]     OBJECT IDENTIFIER}

If this certificate does not contain a SubjectAltName extension, null is returned. Otherwise, a Collection is returned with an entry representing each GeneralName included in the extension. Each entry is a List whose first entry is an Integer (the name type, 0-8) and whose second entry is a String or a byte array (the name, in string or ASN.1 DER encoded form, respectively).

RFC 822, DNS, and URI names are returned as Strings, using the well-established string formats for those types (subject to the restrictions included in RFC 3280). IPv4 address names are returned using dotted quad notation. IPv6 address names are returned in the form "a1:a2:...:a8", where a1-a8 are hexadecimal values representing the eight 16-bit pieces of the address. OID names are returned as Strings represented as a series of nonnegative integers separated by periods. And directory names (distinguished names) are returned in RFC 2253 string format. No standard string format is defined for otherNames, X.400 names, EDI party names, or any other type of names. They are returned as byte arrays containing the ASN.1 DER encoded form of the name.

Return
`MutableCollection<MutableList<*>!>!`	an immutable `Collection` of subject alternative names (or `null`)

Exceptions
`java.security.cert.CertificateParsingException`	if the extension cannot be decoded

getSubjectDN

Added in API level 1

abstract fun getSubjectDN(): Principal!

Denigrated, replaced by getSubjectX500Principal(). This method returns the subject as an implementation specific Principal object, which should not be relied upon by portable code.

Gets the subject (subject distinguished name) value from the certificate. If the subject value is empty, then the getName() method of the returned Principal object returns an empty string ("").

The ASN.1 definition for this is:

subject    Name

See getIssuerDN for Name and other relevant definitions.

Return
`Principal!`	a Principal whose name is the subject name.

getSubjectUniqueID

Added in API level 1

abstract fun getSubjectUniqueID(): BooleanArray!

Gets the subjectUniqueID value from the certificate.

The ASN.1 definition for this is:

subjectUniqueID  [2]  IMPLICIT UniqueIdentifier OPTIONAL
 
  UniqueIdentifier  ::=  BIT STRING

Return
`BooleanArray!`	the subject unique identifier or null if it is not present in the certificate.

getSubjectX500Principal

Added in API level 1

open fun getSubjectX500Principal(): X500Principal!

Returns the subject (subject distinguished name) value from the certificate as an X500Principal. If the subject value is empty, then the getName() method of the returned X500Principal object returns an empty string ("").

It is recommended that subclasses override this method.

Return
`X500Principal!`	an `X500Principal` representing the subject distinguished name

getTBSCertificate

Added in API level 1

abstract fun getTBSCertificate(): ByteArray!

Gets the DER-encoded certificate information, the tbsCertificate from this certificate. This can be used to verify the signature independently.

Return
`ByteArray!`	the DER-encoded certificate information.

Exceptions
`java.security.cert.CertificateEncodingException`	if an encoding error occurs.

getVersion

Added in API level 1

abstract fun getVersion(): Int

Gets the version (version number) value from the certificate. The ASN.1 definition for this is:

version  [0] EXPLICIT Version DEFAULT v1
 
  Version ::=  INTEGER  {  v1(0), v2(1), v3(2)  }

Return
`Int`	the version number, i.e. 1, 2 or 3.

verify

Added in API level 24

open fun verify(
    key: PublicKey!, 
    sigProvider: Provider!
): Unit

Verifies that this certificate was signed using the private key that corresponds to the specified public key. This method uses the signature verification engine supplied by the specified provider. Note that the specified Provider object does not have to be registered in the provider list. This method was added to version 1.8 of the Java Platform Standard Edition. In order to maintain backwards compatibility with existing service providers, this method is not abstract and it provides a default implementation.

Parameters
`key`	PublicKey!: the PublicKey used to carry out the verification.
`sigProvider`	Provider!: the signature provider.

Exceptions
`java.security.NoSuchAlgorithmException`	on unsupported signature algorithms.
`java.security.InvalidKeyException`	on incorrect key.
`java.security.SignatureException`	on signature errors.
`java.security.cert.CertificateException`	on encoding errors.
`java.lang.UnsupportedOperationException`	if the method is not supported